Nathan Birnbaum was born Jan. 20, 1896, on the Lower East Side of New York.

Nathan Birnbaum was born Jan. 20, 1896, on the Lower East Side of New York.

Frank Gorshin was born April 5, 1933, in Pittsburgh, Pennsylvania.

Nathan Birnbaum grew up to be George Burns, a/k/a God.

Frank Gorshin grew up to be Frank Gorshin, a/k/a Marlon Brando, Richard Widmark, James Cagney, Kirk Douglas, Jack Nicholson, Burt Lancaster, dozens of others in simulation over a long career — and, of course, also and memorably The Riddler, one of the oddball no-goodniks of televison's "Batman" series of the 1960's.

Nowadays, Frank Gorshin becomes George Burns eight times a week in a one-man show called Say Goodnight Gracie. Written by Rupert Holmes and directed by John Tillinger, the enterprise has come north from a debut two years ago in Fort Lauderdale and Miami, Florida, for a stand at the Helen Hayes Theatre on West 44th Street, next door to Sardi's. "I was on Broadway in 1970," says actor-comedian-impressionist Gorshin over the phone from his home in Los Angeles, some weeks before the New York opening, "in a show called Jimmy, and now I'm going back to Broadway, 32 years later, and I'm so excited. Well, you always feel good when they ask you back! Even though . . . I never had a picture put up at Sardi's."

Well, maybe they'll put one up now. Gorshin, as previewed via video tape, has George Burns's corrugated-cardboard voice, and bark, and slippered shuffle, and seen-everything eyes gleaming out from behind big black horn-rims, and that single essential George Burns prop — the cigar that goes back and forth, back and forth, to the lips and away without ever being puffed — in short, all of it, the whole gestalt, down to a T. This George also, like the real one, casually intermeshes with the astral voice and laughter of Gracie Allen, or — as it may sometimes be — Didi Conn doing Gracie from somewhere in the wings.

Frank Gorshin never in real life met George Burns, nor ever saw Burns live onstage. What he, like every other American, has seen and heard over the years (and, of course, of late has studied, researched, intently) is the George Burns of radio, television and motion pictures — in particular Burns's Oscar-winning performance as Al Lewis opposite Walter Matthau's irascible Willy Clark in the 1975 movie version of The Sunshine Boys.

"As a matter of fact," says Gorshin, "I just got through doing a six-month bus-and-truck tour of The Sunshine Boys, only I played the Matthau role and Dick Van Patten had the George Burns role."

He himself once starred in a movie, Everything George, "which was not released and never will be, because they ran out of money. It was, oh, seven, eight years ago. What I realized from it was a piece of tape." It was that piece of tape "that my manager at the time, Larry Spellman, brought to the attention of Bill Franzblau, who got intrigued." (William Franzblau is the lead producer and Larry Spellman one of the six other producers of Say Goodnight Gracie.) "I was then at the Claridge in Atlantic City, doing Kirk Douglas, Burt Lancaster, Jack Nicholson, and I also did two minutes of George Burns, right there onstage, without makeup or anything. Bill Franzblau was impressed. He brought Rupert Holmes down to see me, and it was decided that Rupert Holmes was going to write a show and I was going to do it."

Gorshin says that during the four months in Florida, "people would gasp for a minute when I turned around. They think for a second that it is George Burns; some even said that George Burns was 'channeling' [back to earth] through me.

"People ask me how I do these things [his takeoffs]. I have to explain that I wish I could tell you Step 1, Step 2, but it's not so. With George Burns, I just did it by watching him, thinking him, and eventually it was there."

Nathan Birnbaum was 11 years old when he quit school to form and lead The Pee Wee Quartet, his entrance into show business. He was 15 years old and a dance instructor when he changed his name to George Burns. He was 27 and getting nowhere fast when he met and started an act with a San Francisco girl named Grace Ethel Cecile Rosalie Allen.

George Burns lived to be 100. "I'm getting more longevity out of George Burns than anyone I ever did," says Gorshin. "I stay onstage an hour and a half." Over the phone from Los Angeles there comes a sort of George Burns bark. "I told a friend I was going to New York to do a one-man show. He wanted to know if there was anything in it for him." Oy, Riddler, they were saying that even before George Burns was born.